A patient admitted to the oncology unit develops electrolyte abnormalities including hyperkalemia, hyperphosphatemia, and hypocalcemia following initiation of chemotherapy. Which of the following conditions is most likely responsible?

Appeared in: NORCET 10 Mains

Explanation

Tumor Lysis Syndrome (TLS) is an oncologic emergency caused by the rapid destruction of a large number of cancer cells, typically after the initiation of chemotherapy.
The breakdown of these cells releases their intracellular contents into the bloodstream.
This release leads to a characteristic pattern of metabolic abnormalities: hyperkalemia (from potassium), hyperphosphatemia (from phosphate), and hyperuricemia (from nucleic acids).
The resulting hyperphosphatemia causes a secondary hypocalcemia because the excess phosphate binds to serum calcium, lowering its free, active levels.

Option B: Septic shock is primarily an infectious and hemodynamic crisis. While it can cause metabolic acidosis and some electrolyte shifts, it does not produce the classic triad of hyperkalemia, hyperphosphatemia, and hypocalcemia seen in TLS.
Option C: This condition is defined by high levels of serum calcium, which is the direct opposite of the patient's finding of hypocalcemia.
Option D: SIADH is a disorder of water balance, not the electrolyte pattern seen here. It causes the body to retain too much water, leading to dilutional hyponatremia (low sodium).

Clinical Relevance

Nursing practice connection: Use the key finding related to Pathophysiology and hallmark electrolyte imbalances of Tumor Lysis Syndrome (TLS) to guide bedside assessment, documentation, and the next nursing action.
Recognizing the signs of TLS is a critical nursing responsibility, as it is a life-threatening emergency requiring immediate intervention to prevent cardiac arrest and acute kidney injury.
Nursing care for patients at risk for TLS includes aggressive IV hydration, frequent monitoring of electrolytes and renal function, and administration of medications like allopurinol or rasburicase to manage uric acid levels.
What if? If the patient's labs showed hypercalcemia instead of hypocalcemia, the diagnosis would shift to Hypercalcemia of Malignancy. The treatment would be completely different, focusing on hydration and medications to lower calcium levels, such as bisphosphonates and calcitonin.

How to Approach the Question

First, analyze the clinical setting: The patient is in an oncology unit and has just started chemotherapy. This context immediately raises suspicion for treatment-related complications.
Next, identify the key data points in the question: The specific electrolyte abnormalities are hyperkalemia, hyperphosphatemia, and hypocalcemia.
Systematically evaluate each option. Ask yourself, 'Does this condition cause this specific pattern of electrolyte changes?'
Recall or deduce the pathophysiology. Tumor cells are rich in potassium and phosphate. Their rapid destruction would release these substances, explaining the hyperkalemia and hyperphosphatemia.
Connect the findings. The high phosphate level binds with calcium, explaining the secondary hypocalcemia. This unique combination points directly to Tumor Lysis Syndrome.

Concept Tested & Keywords

Concept Tested: Pathophysiology and hallmark electrolyte imbalances of Tumor Lysis Syndrome (TLS).
Stem keywords: oncology unit, chemotherapy, electrolyte abnormalities, hyperkalemia, hyperphosphatemia, hypocalcemia
Lead-in keywords: most likely
Clinical cues: The patient is in an oncology unit and recently started chemotherapy, which are classic risk factors for TLS.
Clinical cues: The specific triad of high potassium, high phosphate, and low calcium is the key diagnostic clue.

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